The operational model for most computer and/or on-chip systems involves the sending of requests from one or more processing units to one or more service modules in the system. Upon receiving a request (i.e., an instruction) from a processing unit, a service module completes the task as requested. Then, there may be responses to be returned from the service module back to the processing unit. It is also very common to have a component in the system to act as both a processing unit and a service module.
Many different ways may be used to deliver requests and responses between processing units and servicing modules. One of the most frequently used methods, for delivering the requests, is by addressing (plus, protection checking). For instance, a request is tagged with a “destination address” and a “source protection identification (ID)”. The destination address tells where the service module(s) is (are) located, and/or how to deliver the request to the service module(s). The source protection ID identifies the processing unit and is used to determine whether the service module(s) should execute the request, or whether the request can be delivered to the service module(s), thus providing access to the service module selectively depending on source identity.
Usually, the number of transistors (often referred to as “gates”) and the resulting gate size (and thus area) of the hardware module (on for example, an integrated circuit) devoted to address decoding and protection ID checking are comparatively large. Additional circuitry, which consumes more power, may also be needed in order to make this decoding and checking hardware dynamic (i.e., configurable) during operation. For a wireless device, especially, where the demand for a smaller chip die size and a lower power consumption is high, a large and power-consuming address decoding and protection-checking module is unacceptable. This presents problems.